必须妥善处理生态目标与生计需要之间的关系——关于黔东南生态文明试验区建设中的问题之一

建设生态文明试验区是黔东南苗族侗族自治州落实生态文明的重要举措,这对黔东南州的发展十分重要。但是,在具体落实过程中也遇到了一些矛盾,其中比较重要的是该如何协调生态目标与生计需要之间的关系。目前对这一矛盾的认识和处理还存在一些不足之处:一是对生态工程建设中的复杂性认识不足;二是生态建设与经济发展的协调不足;三是出台政策单一,配套不足,缺乏相应的救济功能。要解决上述矛盾,一是要科学认识生态文明建设的历史特征和区域特征,建立多元协调的经济社会发展目标;二是必须加大中央财政支付转移,建立分级管理及其相应规划的生态公益林补偿机制;三是建立适应黔东南州地方特色的林业资源建设、利用的合理体系。     

A two-stage realized volatility approach to estimation of diffusion processes with discrete data

This paper motivates and introduces a two-stage method of estimating diffusion processes based on discretely sampled observations. In the first stage we make use of the feasible central limit theory for realized volatility, as developed in [Jacod, J., 1994. Limit of random measures associated with the increments of a Brownian semiartingal. Working paper, Laboratoire de Probabilities, Universite Pierre et Marie Curie, Paris] and [Barndorff-Nielsen, O., Shephard, N., 2002. Econometric analysis of realized volatility and its use in estimating stochastic volatility models. Journal of the Royal Statistical Society. Series B, 64, 253–280], to provide a regression model for estimating the parameters in the diffusion function. In the second stage, the in-fill likelihood function is derived by means of the Girsanov theorem and then used to estimate the parameters in the drift function. Consistency and asymptotic distribution theory for these estimates are established in various contexts. The finite sample performance of the proposed method is compared with that of the approximate maximum likelihood method of [Aït-Sahalia, Y., 2002. Maximum likelihood estimation of discretely sampled diffusion: A closed-form approximation approach. Econometrica. 70, 223–262].     

Joint estimation of technology choice and technical efficiency: an application to organic and conventional dairy farming

This paper proposes an econometric framework for joint estimation of technology and technology choice/adoption decision. The procedure takes into account the endogeneity of technology choice, which is likely to depend on inefficiency. Similarly, output from each technology depends on inefficiency. The effect of the dual role of inefficiency is estimated using a single-step maximum likelihood method. The proposed model is applied to a sample of conventional and organic dairy farms in Finland. The main findings are: the conventional technology is more productive, ceteris paribus; organic farms are, on average, less efficient technically than conventional farms; both efficiency and subsidy are found to be driving forces behind adoption of organic technology.     

A statistical equilibrium model of competitive firms

We find that the empirical density of firm profit rates, measured as returns on assets, is markedly non-Gaussian and reasonably well described by an exponential power (or Subbotin) distribution. We start from a statistical equilibrium model that leads to a stationary Subbotin density in the presence of complex interactions among competitive heterogeneous firms. To investigate the dynamics of firm profitability, we construct a diffusion process that has the Subbotin distribution as its stationary probability density. This leads to a phenomenologically inspired interpretation of variations in the shape parameter of the Subbotin distribution, which essentially measures the competitive pressure in and across industries. Our findings have profound implications both for the previous literature on the ‘persistence of profits’ as well as for understanding competition as a dynamic process. Our main formal finding is that firms' idiosyncratic efforts and the tendency for competition to equalize profit rates are two sides of the same coin, and that a ratio of these two effects ultimately determines the dispersion of the equilibrium distribution.     

非参数核密度估计在异方差模型中的应用

针对非参数核密度估计中最优窗宽的选择在实际建模中的不足,提出了一个新的最优窗宽选择的迭代方法,克服了使用传统的经验法则所带来的局限性。并在此基础上用一种新的非参数核密度估计ML方法应用到了中国股票市场,通过与极大似然估计对比论证了此方法的有效性和可行性。实证分析表明,通过与实际值的模拟对比,运用非参数估计技术得到上证指数日收益率的拟合值要优于极大似然估计的拟合值。     

Do poverty and poor health and nutrition increase the risk of armed conflict onset?

We analyze the effects of improving the economic, food security and health status on the risk of armed cotntectflict onset, focusing on the factors related to the millennium development goals. We employ the discrete-time hazard model that allows us to examine the time-varying effects of socioeconomic factors controlling for the reverse effect of conflict. Our results show that income poverty and poor health and nutritional status are more significantly associated with armed conflict onset than GDP per capita, annual GDP growth, and the ratio of primary commodity exports over GDP. In particular, poor health and nutritional status seems to play a key role in inducing armed conflicts in poor countries. These results indicate that, when a majority of the poor and the malnourished resides in rural areas and depends on agriculture directly or indirectly, investments in public goods for agriculture and rural areas can be effective tools to achieve the multiple goals of reduced poverty, food security and armed conflict, including riots in early 2008 triggered by high food prices. Food policy can be an effective element of efforts to maintain stability.     

How are we doing on poverty and hunger reduction? A new measure of country performance

The paper presents a new composite indicator – the poverty and hunger index (PHI) – to measure countries’ performance toward achieving millennium development goal No.1 (MDG1) on halving poverty and hunger by 2015. Building on the statistical structure of the human development index, the PHI combines all five official MDG1 indicators, thereby generating insights on a country’s net progress towards its own goal, as opposed to progress measured by a single yardstick. Nonparametric analysis on the PHI components provides further evidence on the nature of the relationship between poverty and hunger measures, while cross-country results show significant variance in progress between and within regions. An extension of the PHI allows for consideration of the rate of progress made by each country in its own terms; that is, based on where it needs to be to attain all 5 MDG1 targets by 2015. Countries needing priority attention are identified, as well as areas for future research and recommendations for post-2015 initiatives.     

论物流企业服务的道德目标

物流企业服务的道德目标是卓越服务,即使企业服务主体拥有企业服务可持续发展的道德情怀;拥有超越自身经济利益的道德使命和目的。本文以此为出发点,提出通过企业服务行为来展现其道德目标,从而达到卓越服务。     

Cost-Effective and Stochastic Dominance Approaches to Stochastic Pollution Control

Most economic studies of pollution externalities focus on the relative efficiency or cost-effectiveness of alternative pollution control instruments. Much less attention has been paid to policy goals and objectives. However, a comprehensive pollution control strategy depends on all of these choices. This paper examines several efficiency properties of cost-effective pollution control strategies in a stochastic setting when economic damages from pollution are unknown. A number of policy goals are considered. In this setting and under a primal approach, it is found that certain stochastic dominance conditions must be satisfied for the strategies to exhibit desirable efficiency properties. A dual approach to cost-effective pollution control, which is based on a stochastic dominance objective, is also considered.     

基于GRA&BPNN的广西粮食产量预测研究

[目的]研究粮食产量的影响因素并以其相关性为基础预测粮食产量对实现广西粮食产业的"做强做优"具有重大意义。通常情况下粮食产量与种植技术发展水平、农田耕地面积、土地肥力、气候等诸多因素相关,但是在样本数据不足、数据间关联度不明显的情况下则无法采用回归分析、灰系统等常用预测方法。[方法]文章应用灰色关联分析方法得到水库水量、农田有效灌溉面积、第一产业从业人口、播种面积、除涝面积等5个与广西粮食产量关系最为密切的因子变量,同时取2004~2012年的数据作为学习、训练样本,以2013~2014年的数据为试报样本,并以此建立BP神经网络粮食预测模型。[结果]检验结果表明运用本模型预测粮食产量具有较高的精度和良好的泛化性。[结论]根据模型结果,该文提出提升广西粮食产业发展的可行性建议,即加强水库的管理、引导与粮食产业相关的产业、稳定粮食种植面积、加强洪涝灾害的防御和治理能力、推进农业信息化。